1. Field of the Invention
The present invention relates to a circuit configuration and a corresponding method for implementing a mechanism for simple determination of position minus time in a complex command sequence.
2. Description of the Related Art
In presently known engine control units, often only a complex software architecture and very complex control algorithms are available, which require extensive computing resources. The available control algorithms must typically process highly dynamic input data and calculate output parameters, which also incorporate physical characteristics of particular actuators. Such an output parameter is, for example, in the case of activation of an actuator, the inertia or delay characteristic of the actuator, which makes it necessary, for example, a certain time before an engine reaches a specific rotational angle at which an event is to occur, to trigger this event or an operation associated therewith. The engine is to rotate at different speeds depending on the acceleration or deceleration, so that the rotational angle (position) will in turn be reached at a different point in time as a function thereof. The point in time assigned to the rotational angle therefore changes depending on the change of the parameter. A so-called position minus time calculation permits it to predict when, based on instantaneous time or state parameters, a state is reached in which a planned operation to be carried out is to be carried out or must be triggered.
For example, it is conceivable that in the case of an injection pump, the particular injection as a function of a particular acceleration or deceleration of the engine may always only occur in a specific angle position of the shaft coupled to the injection pump, so that it may be predicted based on a present instantaneous state of the shaft when the corresponding angle position will be reached, so that the injection may occur then. In this case, however, the above-mentioned inertia or delay characteristic of the actuator is to be considered, and also the overall state of all parameters influencing this operation to be carried out, for example, an acceleration or deceleration of the engine itself.
So-called position minus time calculations were heretofore typically carried out in software and distinguished in that the position minus time calculation is recalculated until an optimum position/time value is known. However, this requires a rapid interrupt behavior of the CPU to be available to the system and additionally claims a large amount of computing time. This becomes a problem in particular when there are high engine speeds.
Against this background, it is an object of the present invention to remedy the above-described disadvantages of the software-based position minus time calculation and in contrast thereto to provide a reliable calculation of the corresponding values even at high engine speeds and simultaneously to relieve the CPU available to the system as much as possible from a high interrupt load and complex calculations.